Bartholomaeus (or Bartholomeus) Anglicus, or Bartholomew the Englishman, was a Franciscan monk of the thirteenth century. He is sometimes confused with another Franciscan and Englishman, Bartholomaeus of Glanville, Glanvilla, or Glaunvilla, who died about 1360. Bartholomaeus Anglicus was born in Suffolk, England in the late twelfth century; the exact date is unknown. He studied natural sciences and theology at Oxford under Robert Grosseteste, then went to Paris to study and teach at the university there. He joined the newly-established Franciscan Order around 1224 or 1225, but continued to teach in Paris. In 1231 he went to Magdenburg in Germany to be a lecturer at the studium. It was there that he wrote his encyclopedia, De proprietatibus rerum (On the nature of things, or On the properties of things), some time before 1260 (probably between 1242 and 1247).

In his encyclopedia Bartholomaeus covered all the sciences as known at that time, including theology, philosophy, medicine, astronomy, chronology, zoology, botany, geography, and mineralogy. The work was to serve as instruction for his fellow Franciscans, who were expected to be educated but did not have the time or means to study each discipline individually. The work is in nineteen books (19 being 12 + 7, the 12 signs of the zodiac plus the seven planets, so meaning universality), titled in Latin:

1. De deo (On God)

2. De angelis (On angels)

3. De anima (On the soul)

4. De elementis (On the elements - the four elements; humours of the human body)

5. De hominis corpore (On the human body - the limbs and organs)

6. De etate hominis (On the states of humans - the ages of man; the biblical categories of man and woman)

7. De infirmitatibus (On illness - the meaning and cause of sickness; diseases; medicine and doctors)

8. De mundo et celo (On the earth and the heavens - the matter of the world; the speres and circles of the heavens; the zodiac; the motion of the planets; sun and moon)

9. De temporibus (On time - divisions of the year and day; the seasons)

10. De materia et forma (On matter and form - the element of fire; materia prima)

Bartholomaeus quotes extensively from a wide variety of authors, referring to the works of Greek, Arabian, and Jewish naturalists and medical writers, which had been translated into Latin shortly before. He cites such authorities as Aristotle, Hippocrates, Pliny, Augustine, Boethius, Rabanus Maurus, Solinus, and Isidore of Seville among many others.

The De proprietatibus rerum was an immediate success, and continued to be popular for centuries. It was translated into several languages, including Spanish, French (as Livre des Propriétés des Choses), Dutch (Van de proprieteiten der dingen), and English (translated by John Trevisa). It now exists in over 200 manuscripts and several early printed editions.

The parts of De proprietatibus rerum of interest here are books 12 (birds) and 18 (animals), and perhaps 16 (stones). Only one bestiary, Cambridge, University Library MS. Gg.6.5, quotes extensively from De proprietatibus rerum, but others were influenced by it.